After a minority of SPD Reichstag deputies followed the example of Karl Liebknecht in 1915, who was the first German member of parliament to refuse to approve any further war credits, the majority of the SPD Reichstag deputies excluded the minority from the SPD – not expecting that the minority would be able to reorganise itself – which it did in Gotha during the Easter of 1917, the “historic site” of the 1875 party unification conference between the “Lassalleans” (ADAV/LADAV) and the “Eisenachians” (SDAP). They reappeared in the form of the Independent Social Democratic Party of Germany.
This USPD, of which the der Spartacus League was part until 29 December 1918, must not be understood as a party of those who left the SPD, but rather as one of those who were excluded (at all levels) from the SPD; a party of pacifists rather than of the revolutionary left – with regional variations and concentrations of both currents. Those on the revolutionary left who were permitted to remain in the SPD frequently did so, hoping for “better times”. In January 1919, it was certainly more than simply a few SPD members who rose up in arms against their own SPD government.